from tkinter import *

root = Tk()

root.title("Button")
root.geometry("300x300")

string = StringVar()
string.set("猜猜我是谁？")

label_text = Label(root, textvariable=string)
label_text.pack(padx=10, pady=20)

def change():
  string.set("哈哈，我是小溪流")

button = Button(root, text="变变变", command=change, fg="red")
button.pack()

root.mainloop()
